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September 29, 2009

Gut worms may protect against allergies

by Sam Savage

British and Vietnamese scientists say they've discovered parasitic gut worms, such as hookworms, might help prevent and treat asthma and other allergies.

Researchers led by Dr. Carsten Flohr of the University of Nottingham, and Dr. Luc Nguyen Tuyen of the Khanh Hoa Provincial Health Service in central Vietnam said their study is the largest double-blind, placebo controlled clinical trial to date looking at potential links between hookworm and other gut worm infections and allergic conditions such as asthma and eczema.

The research was conducted in a rural area of central Vietnam where two of every three children have hookworm and other gut parasite infections and where allergies are extremely rare. More than 1,500 schoolchildren ages 6-17 took part in the clinical trial.

The team investigated whether repeated tablet treatments to clear the body of gut worms made it more likely for children to develop allergic conditions. While the treatment did not demonstrate an effect on asthma or eczema, the treated children had a significantly increased risk of having a positive allergy skin test to house-dust mites and cockroaches.

That, the scientists said, suggests gut worms have the potential to tone down human immune responses.

The next step is to understand exactly how and when gut parasites program the human immune system in a way that protects against allergic sensitization, and for such studies, follow-up from birth will be essential, Flohr said.